1 Field of the Invention
The present invention relates to a serum separation sealant for separating serum (or plasma) and blood clot (i.e., "sealant") by centrifugation of blood and to a fine resin particles used for the same.
2. Description of the Related Art
The analysis of the biochemical components of blood is essential in modern medical treatments, and serum separated from whole blood is widely used as the specimens for the analysis of the biochemical components.
Attempts have been made in, for example, U.S. Pat. No. 3,852,194, when centrifuging blood to separate the serum and blood clot, the desired serum is obtained by using a barrier between the two layers (i.e., serum and blood clot), and then decanting the serum without the use of a pipette. Such barriers may be classified as solid materials, liquid materials, or gelatinous (or gel-like) materials. Liquid materials and gelatinous materials are superior in separation performance and separation efficiency compared with solid materials and further are superior in terms of workability. Silicone resins, polyester resins, acrylic resins, and other liquid resins which have a suitable specific gravity and viscosity may be used as liquid materials. When desiring to impart structural viscosity to these liquid resins or when the resin does not have a suitable specific gravity and viscosity, silica, etc. may be dispersed in the liquid resin to form a gelatinous material. Examples of gelatinous or gel-like materials are disclosed in Japanese Unexamined Patent Publication (Kokai) No. 59-68672. When a blood collecting tube is filled in advance with said gelatinous material, it is preferable to use a material with a structural viscosity such that it will not flow in the distribution stage.
On the other hand, when separating the blood, it is necessary to apply as small a centrifugal force (for example, less than 1500G) as possible in a short time (for example, less than 10 minutes) so as to prevent and to suppress effects of hemolysis on the clinical examination values. To promote movement of the gelatinous materials and form a barrier under a low centrifugal force, it is preferable that the viscosity of the gelatinous materials be low. The barrier of the gelatinous material, formed under centrifugation, must be sturdy or firm to prevent breakdown during the decantation of the serum.
Thus, it is necessary that the gelatinous material possesses transport stability and partitioning ability and also exhibits excellent movability.
Japanese Unexamined Patent Publication (Kokai) No. 52-137181 discloses a blood collection tube in which plastic resin spheres having a size of 0.05 to 2.0 mm (e.g., polystyrene) are placed on a gelatinous material layer composed of liquid materials such as liquid polybutadiene and U.S. Pat. No. 3,920,557 discloses the use of beads as a solid barrier. However, these techniques still have problems with decantation and hemolysis.